Percolation-related magnetic coupling and magnetoresistance properties in Fe/Si_1-xAg_x multilayers

In this paper, we present a study of the magnetic coupling and magnetoresistance (MR) properties in Fe/Si_1-xAg_x multilayers with a granular Si_1-xAg_x spacer layer. We have found that, with increasing silver content (x) in a silicon matrix, the magnetic state of multilayers changes from a nonmagnetic coupling state to weak antiferromagnetic around the percolation point of the ～2.4 nm thick spacer Si_1-xAg_x. The MR measurements also reveal an abrupt increase of MR near the same percolation point. These changes are ascribed to the formation of the percolation path in the granular spacer.